53033 FipsDecoder
23031 County FIPS Code

York County

Maine · County seat: Alfred · Active county or equivalent

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FIPS code 23031 is York County, Maine. With a population of 212,691 (2022 ACS estimate), it ranks #2 in Maine and #319 nationally. York County is part of the Portland-South Portland, ME. The state FIPS code for Maine is 23. This code is used in Census Bureau, BLS, EPA, HUD, and USDA federal datasets to identify this county.

County FIPS

23031

State FIPS

23

ME

Population

212,691

2022 ACS · #319 nationally

Density

214.7/mi²

people per sq mile

Land Area

991

sq miles

Urban/Rural

Metro — 250K–1M population

RUCC 2

How This FIPS Code Works

23 031
23 = State FIPS (Maine)
031 = County FIPS

The 5-digit FIPS code 23031 is formed by combining the 2-digit state identifier 23 (Maine) with the 3-digit county identifier 031. Together they uniquely identify York County in every US federal dataset. No two counties share the same 5-digit FIPS code.

Census ACS Data for FIPS 23031

From the 2022 ACS 5-year estimates — the same values you'd retrieve by querying the Census API with county FIPS 23031.

Median Household Income

$79,743

ACS B19013_001E

Poverty Rate

8.0%

ACS B17001 (below poverty level)

Median Age

45.2

ACS B01002_001E

Metropolitan Area

Adjacent Counties (5)

Counties that share a border with York County. Useful for regional analysis — these are the geographies you'd typically include when studying labor markets, commuting zones, or environmental spillovers around FIPS 23031.

Federal Datasets Using Code 23031

FIPS code 23031 appears as the county identifier in the following federal datasets. Analysts joining data across these sources use this code as the common geographic key.

Using FIPS Code 23031 in Code

Common patterns for querying federal datasets by this county's FIPS code. The leading zeros are significant — always treat FIPS codes as strings, not integers.

Census ACS API — Python 23031
import requests

url = "https://api.census.gov/data/2022/acs/acs5"
params = {
    "get":  "NAME,B19013_001E,B01003_001E",
    "for":  "county:031",
    "in":   "state:23",
    "key":  "YOUR_CENSUS_API_KEY",
}
r = requests.get(url, params=params)
data = r.json()  # [[header...], [York County, Maine, income, pop, ...]
SQL — filtering by county FIPS 23031
-- 5-digit combined FIPS (state + county)
SELECT * FROM your_table WHERE county_fips = '23031';

-- Some datasets store state and county separately
SELECT * FROM your_table
WHERE state_fips = '23'
  AND county_fips = '031';

-- ⚠ Never cast to integer — leading zeros are lost:
-- county_fips = 23031 is WRONG for this county
R — tidycensus 23031
library(tidycensus)

get_acs(
  geography = "county",
  variables = c(income = "B19013_001E", pop = "B01003_001E"),
  state     = "23",
  county    = "031",
  year      = 2022
)
Zero-padding reminder: FIPS codes must always be stored and compared as zero-padded strings. 23 (not 23) and 031 (not 31) — losing the leading zeros is one of the most common data-join bugs in federal datasets. Full guide →

ZIP Codes in York County

ZIP codes do not align perfectly with county boundaries — a single ZIP code can span multiple counties, and a county can contain parts of many ZIP codes. The ratios below (from the Census 2020 ZCTA relationship file) show the land area share of each ZCTA that falls within York County. Why FIPS ≠ ZIP →

ZIP Code % in county
03901 100.0%
03902 100.0%
03903 100.0%
03904 100.0%
03905 100.0%
03906 100.0%
03907 100.0%
03908 100.0%
03909 100.0%
03910 100.0%
03911 100.0%
04001 100.0%
04002 100.0%
04005 100.0%
04006 100.0%
04020 100.0%
04027 100.0%
04030 100.0%
04042 100.0%
04043 100.0%
04046 100.0%
04047 100.0%
04048 100.0%
04049 100.0%
04056 100.0%
04061 100.0%
04063 100.0%
04064 100.0%
04072 100.0%
04073 100.0%

Showing top 30 of 36 ZIP codes by residential address share.

Other Counties in Maine